Download DIGESTION

From Start .....to Finish
 Receive
nutrients so the body can use them
 Eliminate the extra components the body
cannot use
 Takes 12-48 hours
 Alimentary Canal: the digestive tract; 8
metres of tubing
 Digestion: chemical and physical
(mechanical) breakdown of food and drink in
a form your body can absorb for use. Through
digestion, the nutrients are made available
to supply you with energy.
 Mouth
 Esophagus
 Stomach
 Small
intestine
 Large intestine
 Rectum
 Accessory organs: liver; pancreas,
gallbladder
 Ingestion
 Mechanical
 Digestion
 Secretion
 Absorption
 Excretion
processing
 We
are going to get to know PHIL in depth
and personal!
 Label
your diagram of ‘Phil’ according to the
numbers assigned to the different parts of
the digestive system (i.e., 1 – mouth)
 Mechanical
process that begins digestion,
begins in the mouth.
 Via the teeth, the saliva (which contains
mucus) and the tongue, food is softened and
mulched in order to be easily pushed and
digested through the rest of the organs.
 Chewing = mastication
 Chewing grinds, moistens, and increases
surface area for chemical reactions
 primary
functions include:
 Mechanical processing
 Assistance in chewing and swallowing
 Sensory analysis by touch, temperature, and
taste receptors
 Release
saliva
 Softens food and begins to breakdown into
food’s nutrients
 Saliva contains the enzyme amylase which
breaks down carbs into simple sugars
 Lubricates and binds food – helps to form a
BOLUS (ball of food to be passed to the next
part of the digestive system)
 Common
passageway for food, liquids,
and air
 Pharyngeal muscles assist in swallowing
 Directs food from mouth to esophagus
A
flap that closes when swallowing so food
goes down the right tube – protects airway
 If opens, you can choke
 Allow
passage from mouth to esophagus
 Prevents backflow from esophagus to mouth
 Pipe
that leads to the lungs
 Breathing
 Epiglottis protects the trachea when
swallowing food
 Passes
food from mouth to stomach
 Muscles in your esophagus push food down
into the stomach
 This is called PERISTALSIS
 Esophagus is protected from crunchy and
acidic food by mucus membranes (i.e., halfeaten chips)
Figure 24.10ac
 Lower
esophageal sphincter
 Stomach acid/food coming up from stomach
= heartburn
 Makes sure food does not go back up and out
 BILE:
a greenish liquid that helps fat mix with
water in the intestine and enables the body to
digest and absorb fat
 Breaks down toxins (i.e., alcohol) and acts as
a filter for your blood
 Stores glycogen to be converted into glucose
when needed
 Adds
enzymes, acids, and fluids
 Churns, mixes, and grinds food into a liquid
mass (Mechanical breakdown of food)
 Peristalsis continues to grind food up
 HCL attacks food
 Bulk storage of undigested food
 Lined with mucus membranes that stop the
stomach from eating itself
Figure 24.12b
 Pepsin/rennin
– breakdown proteins
 Gastric lipase – breakdown fats
 Amylase – continue breaking down carbs
 DIGESTION
TIME IN THE STOMACH
 Carbs = 1-2 hrs.
 Protein = 3-5 hrs.
 Fats = up to 7 hrs.
 Leaving
the stomach, food is now a thick
fluid called CHYME.
 The chyme passes through the pyloric
sphincter
 The sphincter releases food a little at a time
to help ensure the best possible absorption
of nutrients in the small intestine
 Secretes
pancreatic juices, an enzyme-rich
fluid (thousands of enzymes) that continues
to reduce food to small molecules.
 It also releases bicarbonate to neutralize the
acidic fluid from the stomach.
 Releases and monitors insulin and glucagon
secretion - for glucose control
Figure 24.18ac
 Conducts
pancreatic juices from the
pancreas to the small intestine
 Stores
bile from the liver until needed.
 Allows
passage from stomach to small
intestine.
 Conducts
bile from the gallbladder to the
small intestine
 Secretes
enzymes that digest all energyyielding nutrients and releases bicarbonate
to neutralize acidic chyme that enters the
small intestine.
 Smaller in diameter than the large intestine
(10 feet in length)
 *digestion and absorption occur mainly in the
small intestine
 Through absorption, nutrients are made
available to the body cells in the small
intestine
Three subdivisions:
 Duodenum - most digestion takes place
here
 Jejunum - absorption of nutrients
 Ileum - absorption of nutrients
 The
large, tennis court size area allows for
maximum absorption
 Numerous folds in the intestine are called
VILLI, and in turn they are covered with
more projections called MICROVILLI
 Each microvilli is designed to absorb a
certain nutrient and not any other.
 The
simplest of nutrients are absorbed first,
and the more complex are absorbed further
down the intestine
 By the time the food reaches the end of the
small intestine, it is mostly water, dissolved
minerals and indigestible fibre.
 These substances are absorbed ‘as is’
 Sugars/carbs are broken down first, then
proteins, then fats (just like in the stomach)
 Allows
passage from the small intestine to
the large intestine
 Prevents backflow from the large intestine
 Stores
lymph cells
 Shrunken remainder of a large and normal
intestine of a remote ancestor
 Reabsorb
water and compact material
into feces
 Absorb vitamins produced by bacteria (K,
B12)
 Store fecal matter prior to defecation
 Last
portion of the digestive tract
 Terminates at the anal canal
 Internal and external anal sphincters
 Stores feces prior to elimination
 Holds
rectum closed and opens to allow
elimination
Basic Overview of Target Areas
 Chewing
and swallowing with little digestion
 Carbohydrate digestion begins
 Collecting
and churning with some digestion
 Carb digestion continues
 Proteins begin to digest
 Fat separates from water
 Digesting
and absorbing
 Sugars begin to be absorbed
 Fat emulsified – broken down – absorbed
 Protein – broken down and absorbed
 Vitamins and minerals – absorbed as is
 Reabsorbing
and eliminating
 Fluid and some minerals are absorbed
 Most fibres not digested – push through
digestive tract
 Excreted as feces
 Some fat and cholesterol bind to fibre and
are also excreted
 When
a piece of food slips into the trachea
and becomes lodged
 Waves
of peristalsis in the reverse direction
 ‘reverse peristalsis’
 Contents of stomach are propelled up
through esophagus to mouth
 Adaptive mechanisms to rid itself of
something irritating
 If severe and long enough – extend beyond
the stomach and carry contents of the
duodenum with its green bile up the
esophagus – very acidic
 Frequent,
loose watery stools
 Intestinal contents have moved too quickly
through intestines for fluid absorption to
take place
 Causes: food, medications, stress, etc.
Colitis: refers to an inflammation of the colon
and is often used to describe an inflammation of
the large intestine
 Symptoms of colitis may include: abdominal
pain, loss of appetite, fatgue, diarrhea,
cramping, urgency,and bloating.

Irritable bowel syndrome: characterized most
commonly by cramping, abdominal pain,
bloating, constipation, and diarrhea.
 Normal motility, or movement, may not be
present in the colon of a person who has IBS. It
can be spasmodic or can even stop working
temporarily. Spasms are sudden strong muscle
contractions that come and go.

 Pass
stools that are difficult or painful to
expel, or reduced frequency of bowel
movements
 Some causes: too busy (water removed), lack
of physical activity, lack of fibre
 Fibre helps to prevent constipation
 Diverticulosis: intestinal walls develop bulges
in weakened areas – bulging pockets entrap
feces and then become painfully infected
and inflamed
 Laxatives and enemas are unnecessary
 Belching:
results from swallowing air (eating
slowly can help prevent that)
 Carbonation
and chewing gum can
exacerbate the problem
 Gas
(flatulence): is the expulsion through
the rectum of a mixture of gases that are byproducts of the digestion process
 Flatus (gas) is brought to the rectum by the
same peristaltic process which causes feces
to descend from the large intestine. The
noises commonly associated with flatulence
are caused by the vibration of the anal
sphincter, and
occasionally
by the closed
buttocks
 Painful
sensation a person feels behind the
breastbone when the lower espophageal
sphincter allows the stomach contents to
reflux into the esophagus
 Causes: eat or drink too much, tight clothing,
food intolerances
Erosion of the top layer of cells from an area
(stomach or duodenum)
 Erosion leaves underlying layers of cells
unprotected and exposed to gastric juices
 Sensitivities, disease promoting diets, infection,
excessive gastric acid secretion, and stress can
be causes
 Burning or gnawing feeling in the stomach area
lasting between 30 minutes and 3 hours
commonly accompanies ulcers.
 Pain is usually caused by the ulcer but it may be
aggravated by the stomach acid when it comes
into contact with the ulcerated area.

 http://health.howstuffworks.com/human-
body/systems/digestive/adam-200142.htm
 The
scoop on poop article
 Sizing
up your stool
 http://www.scribd.com/doc/57795072/Stool
s-Graphic
 http://www.doctoroz.com/videos/poop-
primer
 dr_oz_poo_video.mp4